Law is a system of rules that people use to regulate their interactions and enforce the rights of all members of a society. The precise definition of law is a matter of long-running debate, with many books and articles containing different ideas about and definitions of the concept.

A central part of law is the judiciary, a group of judges who resolve disputes and determine guilt or innocence in criminal cases. Some countries have a single judge who makes decisions for all cases, while others have groups of judges or magistrates that make decisions about particular types of cases (like family law or immigration law).

The legislative branch of the government sets laws on how people can live together and do business with each other. In most countries, the legislature consists of a group of politicians who are elected by a governed population to create and vote on laws. Some countries have a constitution that establishes the overall framework of laws, while other governments create more detailed laws, such as a tax code or a health care bill. Private individuals can also create legal documents, such as contracts or arbitration agreements, that have enforceable legal force.

The main areas of law include contract law, which governs the terms that people agree to in business transactions; property law, which defines a person’s rights and obligations toward tangible things like land or buildings, and intangible possessions, such as money, cars, or clothes; and criminal law, which prevents crime and punishes those who break the law. Other specialties of law include medical law, family law, environmental law, and banking and financial regulation.